The present invention relates to a positive photoresist composition for use in the production of a semiconductor integrated circuit device, a mask for the production of an integrated circuit, a printed board, a liquid crystal panel and the like.
The positive photoresist composition includes a chemical amplification-type photoresist composition described in U.S. Pat. No. 4,491,628 and European Patent 29,139. The chemical amplification-type photoresist is a pattern-forming material of generating an acid on the exposed area upon irradiation with radiation such as far ultraviolet ray and causing a reaction using the acid generated as a catalyst to change the solubility in a developer of the areas irradiated or not irradiated with the active radiation and thereby form a pattern on the substrate.
The chemical amplification positive photoresist composition can be roughly classified into a three-component system comprising an alkali-soluble resin, a compound capable of generating an acid upon exposure to radiation (photo-acid generator) and a dissolution-inhibiting compound for an alkali-soluble resin having an acid-decomposable group, a two-component system comprising a resin having a group capable of becoming alkali-soluble upon reaction with an acid and a photo-acid generator, and a hybrid system comprising a resin having a group capable of decomposing upon reaction with an acid and becoming alkali-soluble, a low molecular dissolution-inhibiting compound having an acid-decomposable group, and a photo-acid generator.
Various techniques have been known to improve the performance by mixing two or more resins capable of decomposing under the action of an acid and increasing in the solubility in an alkali developer (acid-decomposable resin), which are used in the above-described chemical amplification-type photoresist composition.
However, these techniques have a problem in the shortening performance. The term xe2x80x9cshortening performancexe2x80x9d means a phenomenon that the length in the longitudinal direction of a pattern in a line-and-space pattern is shortened.
Accordingly, the object of the present invention is to provide a chemical amplification-type positive photoresist composition free of occurrence of shortening of a line pattern edge part (in the longitudinal direction).
Under these circumstances, the present inventors have made extensive investigations, as a result, found that the above-described object can be achieved by using a positive photoresist composition having two kinds of resins each having an acid-decomposable group of specific structure. The present invention has been accomplished based on this finding.
More specifically, the positive photoresist composition of the present invention is constructed as follows.
(1) A positive photoresist composition comprising:
(a) a resin (A) having a structural unit containing a group represented by the following formula (X) and capable of decomposing under the action of an acid to increase the solubility in an alkali developer,
a resin (B) having a structural unit containing a group represented by the following formula (Y) and capable of decomposing under the action of an acid to increase the solubility in an alkali developer, and
(b) a compound capable of generating an acid upon irradiation with actinic rays or radiation: 
wherein R1 and R2, which may be the same or different, each represents a hydrogen atom, a linear, branched or cyclic alkyl group which may have a substituent, m represents an integer of 1 to 20, Z represents 
wherein R3 represents a linear, branched or cyclic alkyl group which may have a substituent, an aryl group which may have a substituent, or an aralkyl group which may have a substituent, and n represents an integer of 0 to 5;
wherein R4 represents a lower alkyl group having from 1 to 4 carbon atoms.
(2) A positive photoresist composition comprising:
(a) a resin (Axe2x80x2) having structural units represented by the following formulae (I), (II) and (III) and capable of decomposing under the action of an acid to increase the solubility in an alkali developer,
a resin (Bxe2x80x2) having a structural unit represented by the following formulae (IV), (V) and (VI) and capable of decomposing under the action of an acid to increase the solubility in an alkali developer, and
(b) a compound capable of generating an acid upon irradiation with actinic rays or radiation: 
wherein R5 represents an acid-stable group, W represents a group represented by formula (X), x and y each represents a number of 1 to 100, and z represents a number of 0 to 100, provided that x+y+z=100; 
wherein R6 represents a hydrogen atom or a methyl group, R7 represents a linear, branched or cyclic alkyl group, an aryl group which may have a substituent or an aralkyl group which may have a substituent, Wxe2x80x2 represents a group represented by formula (Y), xxe2x80x2 and yxe2x80x2 each represents a number of 1 to 100, and zxe2x80x2 represents a number of 0 to 100, provided that xxe2x80x2+yxe2x80x2+zxe2x80x2=100.
(3) The positive photoresist composition as described in (1) or (2), wherein the compound (b) capable of generating an acid upon irradiation with actinic rays or radiation is a compound having a sulfonium salt structure or a compound having a diazodisulfone structure.
(4) The positive photoresist composition as described in (1) or (2), wherein the compound (b) capable of generating an acid upon irradiation with actinic rays or radiation is a mixture of a compound having a sulfonium salt structure and a compound having a diazodisulfone structure.